This invention relates generally to the field of signal transmission systems, and more particularly to a suspended transmission line with an embedded amplifier.
Microwave and radio frequency circuits are generally implemented by interconnecting amplifiers, antennas, transmitters, receivers, and other components by a series of transmission lines. The transmission lines propagate microwave and radio frequency energy between the components of the circuit.
Transmission lines are generally implemented as waveguide pipes, striplines, and/or coaxial cables. Waveguide pipes are often impractical, however, because of the difficulty of installation and the size and weight is excessive for many applications. Striplines and coaxial cables are more compact and easier to install, but use special materials and fabrication processes that lead to high transmission line cost.
Further adding to the expense of microwave and radio frequency circuits is the expense of implementing amplifiers, antennas, and other components within the circuit. Typically, each component is implemented in a specially fabricated mechanical housing such as an aluminum box having signal, digital, and power connectors. These mechanical housings must generally be designed, engineered, and machined with tight tolerances for microwave and other high frequency applications. In addition, drawing packages need to be generated and maintained for each housing. Connectors must also be thermally matched to the mechanical housing.
The present invention provides a transmission line amplifier that substantially eliminates or reduces the problems and disadvantages associated with prior methods and systems. In particular, the amplifier is embedded into a suspended transmission line for use in microwave and radio frequency applications.
In accordance with one embodiment of the present invention, a suspended transmission line with an embedded amplifier includes a support layer and a conductor supported on the support layer between first and second plates each having a ground plane. The conductor includes an input section and an output section. A propagation structure is positioned between the first and second plates to substantially contain an electric field generated by a signal transmitted on the conductor. An amplifier is coupled to the input and output sections of the conductor and is at least substantially disposed between the first and second plates. The amplifier operates to amplify an input signal received on the input section to generate an output signal on the output section.
Technical advantages of the present invention include providing a low cost and space efficient transmission system. In particular, amplifiers and other elements are embedded into the transmission line substantially without degradation in line performance. The amplifiers may be low noise and power amplifiers. Other embedded elements may be high power broadband combiners, filters, diplexers, and other passive elements as well as mixers, multipliers, switches, and other active elements. As a result, the transmission line structure is self-contained and includes fewer parts. The cost of designing, engineering, constructing, and maintaining separate mechanical housings for each element is minimized.
Another technical advantage of the present invention includes providing an improved power amplifier structure for microwave and radio frequency applications. In particular, the power amplifier is embedded within and integral with a suspended transmission line. As a result, separate substrates and carriers for the amplifier are eliminated. Separate transmission line connectors for the amplifier are also eliminated. Thus, the power amplifier may be constructed at relatively low cost.
Other technical advantages of the present invention will be readily apparent to one skilled in the art from the following figures, description, and claims.